Serious talk of a sequel to “Mamma Mia!” continues. Dubbed “Grandmamma Mia!” by the movie’s star, Meryl Streep (pictured), the project would probably center on divorce. Since most of Abba“s up-tempo songs have already been used, the sequel would have to plunder the band’s most depressing tunes. As if the very idea of a sequel weren’t depressing enough!